This disclosure relates to an improved tank for transporting fluids, and in particular, to a tank with a wide ingress-egress opening, stairs and horizontal baffles.
Dust control and mitigation is a major concern for many industries. For example, in the mining industry, the general construction industry and the highway construction industry, dust poses potential safety and health issues at the work site and the surrounding areas. Dust may affect operational safety by reducing visibility and interrupting traffic patterns. Dust may also cause potential environmental issues by adversely affecting air quality, which may lead to long term health issues and may make general working conditions uncomfortable or intolerable.
To address these issues, water from water tanker vehicles is sprayed onto the surface soil to control dust at the site and to prevent dust from drifting to surrounding areas. Safe operation of the water tanker vehicle is of paramount importance and requires a stable tank on the vehicle. A stable tank reduces fluid motion and surging during vehicle acceleration, deceleration, turning, and movement over various surfaces. The tank should control fluid motion at all fluid levels, but in particular at levels less than full, because the fluid tends to move more and exert greater forces on the tank at levels less than full. By controlling fluid motion, the magnitude of the forces and overturning moments imparted to the vehicle by the water tanker are reduced, providing a more stable and safer operating vehicle.
Safe manufacture and maintenance of the tank requires access to the interior of the tank for construction and periodic inspection, cleaning and maintenance. Typically, tank designs and baffle configurations are subject to confined space safety regulations. For example, in the United States, the Occupational Safety & Health Administration (“OSHA”) defines a confined space as a space that: (1) is large enough and so configured that an employee can bodily enter and perform work; and (2) has limited or restricted means for entry or exit (for example tanks, vessels, silos, storage bins, hoppers, vaults, and pits are spaces that may have limited means of entry); and (3) is not designed for continuous employee occupancy. Other regulatory guidelines, specifications, and requirements may be applicable depending on the location where manufacturing, operation, and maintenance activities occur.
A permit may be required to enter or perform work in certain types of confined spaces. For example, OSHA defines a permit-required confined space as a confined space that has one or more of the following characteristics: (1) contains or has the potential to contain a hazardous atmosphere; (2) contains a material that has the potential for engulfing an entrant; (3) has an internal configuration where an entrant may become trapped or asphyxiated by inwardly converging walls or by a floor that slopes downward and tapers to a smaller cross-section; or (4) contains any other recognized serious safety or health hazard. Only specially trained personnel are allowed to enter a permit-required confined space for any purpose and they may only enter that confined space after receiving approval from an entry supervisor. An attendant, trained in entry and rescue procedures, must monitor the entrant at all times when working in permit-required confined spaces. Once inside a permit-required confined space tank, it may be cumbersome and difficult for personnel to maneuver around the internal baffles of the tank, due to the baffle configuration or small access openings in the baffles. As a result, manufacturing and maintaining the tank interior can be a time consuming process with numerous hazards that must be abated.
Performing work in a permit-required confined space is also very expensive due to the additional training, monitoring, personnel, permits and written procedures that are required for such activities to occur. Prior to entering a permit-required confined space, the internal atmosphere must be tested to ensure that conditions are safe for personnel. To mitigate air quality issues and address other potentially hazardous atmospheric conditions within the permit-required confined space, ventilation systems and personal respirators are often utilized. Continuous forced air ventilation may be provided and directed to all areas where personnel are present. It is important that the air supply is from a clean source and that the air supply will not increase any hazards in the permit-required confined space. Thus, existing water tanks that may fall under confined space regulations have numerous shortcomings.